1. Technical Field
The present invention generally relates to a casing structure, and more particularly, to a cover structure for an outdoor casing.
2. Related Art
The need to install large electronic apparatuses outdoors has been rising gradually in this information era. These electronic apparatuses must be put inside outdoor casings to avoid deterioration caused by the sunlight and the rain. Nowadays the most frequently seen outdoor casings are outdoor telecommunication casings. Outdoor telecommunication casings are used when the machine room of a telecommunication company and the users' equipment are too far apart. These casings can be connected to the machine room and the users' equipment through optical fiber, cable, or other communication lines. The electronic apparatuses in these casings can repeat or amplify the attenuated signal so as to ensure the user's communication quality.
As shown in FIG. 1 and FIG. 2, a conventional outdoor telecommunication casing 10 has a containing space 20 in its interior for communication equipment to be installed therein. A convex part 30 extends from the top periphery of the casing 10. The bottom periphery of the convex part 30 has some air vents 301 that are connected to the containing space 20. The casing 10 further has a fan 40 above the containing space 20. The fan 40 can guide external air into the containing space 20, causing the incoming air to absorb heat from the electronic apparatus inside the casing 10, and then bring the heat out through the air vents 301. This process can dissipate the heat accumulated in the casing 10, and stabilize the operation of the electronic apparatus inside the casing 10.
However, the outdoor telecommunication casing 10 is not good at repelling water. If there is a storm, the horizontal arrangement at the bottom rim of the convex part 30 will gather some rain. Strong wind will blow the accumulated water into the air vents 301 and then into the top of the casing 10. The water will flow into the containing space 20 through the fan 40 or other gaps. The water will make the containing space 20 moist, and even will cause the communication apparatus to malfunction. Even if the water enters the containing space 20 is not much, some components may still be damaged. If a lot of water enters the containing space 20, then the communication apparatus may be soaked in the water and breakdown as a whole.